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Improved Data for Mechanistic-Empirical Pavement Design for Concrete Pavements
Abstract and Figures
The Mechanistic-Empirical Pavement Design Guide (M-EPDG) is a state-of-the-practice tool for pavement analysis and design. M-EPDG has been incorporated into the AASHTOware Pavement ME Design software program, and local calibration is necessary for optimal performance. To support NCDOT in use of the Pavement ME Design software for design and analysis of portland cement concrete (PCC) pavements, as well as to meet the need to support the decision to move forward with PLC concrete specifications for future NCDOT projects, a variety of PCC pavement mixtures were developed, batched, and tested. Mixtures included several coarse aggregates, Type I/II ordinary portland cement (OPC), PLC, fly ash from two sources, and fine aggregates (manufactured sand and a natural sand) used in North Carolina (NC). PLC used in these mixtures were produced by intergrinding with one of the OPCs used in the study. Tests to determine the mechanical and thermal properties of the concrete mixtures, as well as several durability performance tests were performed. A catalog of PCC characteristics for use as inputs in the Pavement ME Design software was prepared, and the impact of the new suggested inputs on NC concrete pavement design were evaluated.
The cement type (OPC or PLC) used does not highly influence the results for the suite of tests used to determine the concrete inputs for M-EPDG. Comparable performance of the PLC provides incentive to NCDOT for use of this more sustainable alternative to OPC. Although the type of coarse aggregate utilized in this study did not highly influence the laboratory test results supporting the recommended M-EPDG PCC inputs, the fine aggregate type utilized in the mixture (manufactured sand versus natural sand) did have a significant influence on two thermal PCC inputs: coefficient of thermal expansion (CTE) and thermal conductivity. A sensitivity analysis was performed to identify the changes in predicted distresses for a range of each PCC input. Several typical North Carolina concrete pavements were analyzed using previous and newly suggested PCC inputs using the original design constraints. Findings offer insight into the potentially longer service life of concrete pavements designed and constructed in the past by NCDOT. Use of the new PCC input values may result in the design of slightly thinner concrete pavements in the future. Thinner pavements will reduce the amount of materials used in pavement construction, resulting in lower costs and environmental impact of concrete pavement. The benefits of deciding to reduce PCC thickness should be weighed against the risks associated with under-prediction of traffic or section loss associated with one or more diamond grinding treatments during the service life of the pavement, as well as the service life benefits that could be obtained by using a thicker PCC pavement.
As expected, results indicate use of fly ash in pavement concrete should improve durability performance. Use of PLC alone (without fly ash) did not provide distinct durability performance advantages, when compared to OPC. However, if PLC is utilized with fly ash in concrete mixtures, enhanced durability performance could be anticipated. Due to the delayed strength gain of fly ash mixtures, use of 28-day compressive strength as a PCC input in MEPDG may be unsuitable. A strong correlation was found between surface resistivity test results and rapid chloride permeability test (RCPT) results for all mixtures included this study. Findings of a limited LCA offered insight into the decrease in predicted total criteria air pollutant emissions associated with increased use of fly ash and PLC, providing confidence to NCDOT that use of PLC and fly ash in concrete infrastructure should provide environmental and sustainability benefits, as mandated by the MAP-21 legislation.
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... As agencies in the United States and abroad strive to improve both the economy and sustainability of their pavement infrastructure, research to better understand the influence of different types of data will help to justify the costs associated with the collection of site-specific data and will support the efforts to quantify the benefits of design changes and alternative approaches [9,10]. The specifications used in China are the specifications of highway cement and concrete pavement design (JTG D40-2002). ...
... For example, the Florida Department of Transportation (FDOT) study identified the significance of the PCC property measurement and the consequential use of hierarchy level one for important and large-scale projects, as the resultant pavement structure differed up to three inches in thickness for the same concrete mixture [23]. In a study for North Carolina rigid pavements, Cavalline et al. [9,10] found that default MEPDG inputs were conservative, and new locally representative input values measured via a laboratory study would result in a design pavement thicknesses up to 1 inch thinner than what is currently being utilized. ...
The mechanistic-empirical pavement design guide (MEPDG) is a commonly accepted design principles guide that aids in jointed plain concrete pavement (JPCP) design and performance analysis. The MEPDG uses three different design parameter input levels, referred to as level one, level two, and level three, providing increasing confidence in the analysis at the lower numbered levels, which use more locally relevant (level two) or project-specific (level one) data. The state-of-the-art pavement ME software (version 2.6.2) uses MEPDG design principles to predict pavement performance. The three performance indicators for JPCP systems (international roughness index (IRI), joint faulting, and transverse cracking) experience significant changes when simulating under a different input level. The IRI and faulting indicator changed by 78 percent when using inputs varying from level one to level three, with the cracking indicator change being more severe at 87 percent. To accommodate the change in performance indicator values between input level one and input level three, increasing the concrete slab thickness is necessary to achieve comparable pavement performance. An increase in the Portland cement concrete (PCC) layer from one inch to two inches is required when input level three simulations are performed, demonstrating the economic and sustainability benefits of using project-specific level one inputs. Understanding the impact of simulation input levels will help to meet design and sustainability goals and improve the lifecycle performance of JPCP systems.
... Some stations also collect snow depth and snowfall information. The ISD database undergoes a meticulous quality control process before distribution [14] [15]. However, data quality issues still remain in the database [15]. ...
... The ISD database undergoes a meticulous quality control process before distribution [14] [15]. However, data quality issues still remain in the database [15]. These issues are dealt with effectively through additional quality assurance algorithms. ...
... A-14 It can be observed from Table 4 and from Figure 11 (below) that the SAM air content measured at the plant tended to consistently run slightly lower than the ASTM C231 air content measured at the paver using the Type B meter. The reason for this is not readily evident, and many studies including those at UNC Charlotte have shown strong agreement between the SAM and Type B meter (Tanesi et al. 2015, Cavalline et al. 2018, Cavalline et al. 2019. It is theorized that measurement of the air void system using the SAM at the paver (instead of at the plant) may have provided both total air contents closer to that of the ASTM C231 test and potentially, lower SAM numbers (Ley 2019). ...
... It is recommended that in future studies, the SAM test be performed at the same location as the Type B meter to provide a direct comparison. C666 Procedure A test (Ojo 2017, Cavalline et al. 2018, Cavalline et al. 2019. In Figures 12a and 12b, the relationship between the SAM number and the air content measured by the SAM device ( Figure 12a) and Type B pressure meter ( Figure 12b) are shown. ...
Performance engineered concrete mixtures (PEM) include optimized mixture designs and advanced quality assurance methods to provide improved economy, durability, and sustainability of concrete mixtures. The North Carolina Department of Transportation (NCDOT) has supported several research studies to support collection of data for targeted PEM testing technologies and some prescriptive measures. Through these studies, performance targets and proposed specification provisions have been developed for surface resistivity, super air meter (SAM), and shrinkage. In 2018, NCDOT applied for funds to support PEM implementation as part of FHWA’s “Demonstration Project for Implementation of Performance Engineered Mixtures/AASHTO PP 84.” Funding to support three categories of implementation were secured. This report details the efforts associated with these implementation funds, which included (1) use of PEM tests for QC and acceptance (shadow purposes only) at a concrete paving project, (2) analysis of data from the PEM implementation project and integration of this data with that obtained from other laboratory studies supporting the PEM initiative, (3) development of technology transfer documents (test procedures for PEM tests compatible with NCDOT’s Concrete Field Technician Study Guide), (4) development and delivery of a seminar/workshop to support technology transfer to NCDOT’s division and region personnel, and (5) preparation of the final report of the PEM implementation project to fulfill the required deliverable to FHWA. Data and findings from the implementation site supported specification recommendations made by UNC Charlotte as part of PEM research, and informed additional shadow testing at an implementation project focused on structural concrete. A final report was prepared and submitted to FHWA to fulfill requirements of receipt of PEM Implementation Funds, and a number of additional presentations were made to publicize NCDOT’s PEM efforts. Technology transfer tools produced and disseminated as part of this work will provide continued opportunities to educate NCDOT personnel at the divisional and regional levels, as well as other stakeholders, about the PEM initiative and provide training on the PEM tools targeted for use by NCDOT. Advancements made through NCDOT’s PEM efforts will impact specifications, design, and construction. More durable, sustainable concrete mixtures will be specified and used in North Carolina highway infrastructure, resulting in cost savings for construction, quality assurance, and extended life of concrete pavements and bridges.
... The AC rutting when using VWS varied up to 1.6 times compared to those by existing weather stations (Saha et al., 2014). Godfrey et al (2015) described the interpolation technique used in the PMED software as a simple weighting algorithm that operates by averaging the influence of nearby weather stations based on the inverse of the distance to each station. Since the weighing algorithm was applied in previous studies to filling gaps in stations with missing data, the author placed concerns on the effectiveness of this method in places with varying topography and along coastal areas which are highly accompanied by large discontinuity in meteorological surface variable. ...
... All 3 analyzed NARR grids for the months of January and July with a 5 years data span produced lower R 2 values than the established 0.9 limit. From these results the author discouraged the used of VWS in the MEPDG software especially with respect to long distances since it results to failure of a realistic time series of hourly climatic data (Godfrey, 2015). ...
Pavement Mechanistic Empirical Design (PMED) allows users to create Virtual Weather Stations (VWS) in locations where no nearby weather stations exist. VWS quality has faced several critiques through its implementations in PMED. PMED adopts the gravity model in its VWS creation process. MATLAB codes were used in comparing the error convergence of the gravity model interpolation technique and that by a Radial Basis Function (RBF). RBF interpolation showed very fast error convergence with the increase in number of interpolation data as compared to the gravity model. Contour plots emphasized the quality of interpolation where the RBF model produced well defined contours with a wider range of output than the gravity model. PMED software was used for further assessments of the quality of its VWS and RBF VWS considering climatic summary and pavement predicted distresses outputs. In most cases, the RBF VWS outperformed the current PMED VWS outputs.
... Moreover, several studies have been able to correlate electrically based resistivity to other durability tests, including water absorption, migration, and rapid chloride permeability testing. [16][17][18] Among the available durability tests, electrically based resistivity has been proven to correlate well with microstructural and transport properties of concrete. [18][19][20][21][22] By relying on the correlation between resistivity and fundamental pore structure features, 21 different research studies have shown that resistivity can be used to characterize the performance of concrete mixtures in terms of: ...
Multiple initiatives advocate for reducing embodied carbon (i.e., greenhouse gas emissions) associated with concrete production. Even though readily implementable strategies exist, practitioners are concerned that reducing embodied carbon emissions may adversely affect concrete performance and durability, resulting in detrimental effects from a life cycle perspective. To address such concerns, this study investigated the correlations between embodied carbon of concrete mixtures, mixture design parameters, and experimentally measured mechanical and durability properties. The analyzed datasets included 145 mixtures, featuring a variety of mixture designs from laboratory and field studies. The results indicate that the cement content is the most significant predictor of global warming potential (GWP) and that considerable GWP savings can be achieved by reducing and replacing cement without compromising performance. Clear correlations of GWP with compressive strength were not identified, while the results demonstrated that reduced GWP and increased electrically based resistivity (the utilized durability indicator) often occur in synergy.
... Before distribution/sharing, the ISD database undergoes a meticulous quality control process (Smith et al., 2011;Lott, 2004). In spite of rigorous quality control, there are data quality issues with the database (Godfrey, 2015). Additional quality assurance algorithms are therefore applied at the regional-level. ...
Data from weather stations at airports, far away locations or predictions using macro-level data may not be accurate enough to disseminate visibility related information to motorists in advance. Therefore, the objective of this research is to investigate the influence of contributing factors and develop visibility prediction models, at road link-level, by considering data from weather stations located within 1.6 km of state routes, US routes and interstates in the state of North Carolina (NC). Four years of meteorological data, from January 2011 to December 2014, were collected within NC. Ordinary least squares (OLS) and weighted least squares (WLS) regression models were developed for different visibility and elevation ranges. The results indicate that elevation and cloud cover are negatively associated with low visibility. The chances of low visibility are higher between six to twelve hours after rainfall when compared to the first six hours after rainfall. A visibility sensor was installed at four different locations in NC to compare hourly visibility from the selected regression model, High-Resolution Rapid Refresh (HRRR) data, and the nearest weather station. The results indicate that the number of samples with zero error range was higher for the selected regression model compared with the HRRR and weather station observations. Keywords: Environmental sciences, Elevation, Weather station, Regression, Visibility, HRRR, Precipitation, Sensor
... The testing program to determine concrete fresh properties and mechanical and thermal M-EPDG concrete inputs is shown in Table 4, along with information on replicates. Other durability testing was performed as part of this study, but the results are presented in other publications (Medlin 2016;Cavalline et al. 2018). Heat capacity --Low sensitive to insensitive Guclu and Ceylan (2005) Tests for heat capacity and thermal conductivity are rarely included in studies to determine concrete inputs for M-EPDG due to issues with the recommended test methods (Shin and Kodide 2012). ...
A catalog of locally appropriate Mechanistic-Empirical Pavement Design Guide (M-EPDG) inputs was developed for North Carolina Department of Transportation (NCDOT) rigid pavements using 18 concrete mixtures produced with two ordinary portland cements (OPCs), portland limestone cement (PLC), two fly ashes, and local aggregates. Equivalent mechanical and thermal performance was found between mixtures using OPC and PLC, supporting use of these sustainable cements. Tests for coefficient of thermal expansion (CTE), thermal conductivity, and heat capacity revealed default values are very conservative for North Carolina use. Varying coarse aggregate type did not greatly influence performance. However, fine aggregate type (manufactured or natural sand) significantly influenced concrete thermal properties. Sensitivity analysis findings were similar to other studies. Analyses for thermal conductivity and heat capacity provided insight into the effects of these infrequently measured inputs on predicted performance. The predicted performances of pavement sections with calibrated input values outperformed sections that were designed using the default input values for concrete currently used. Thinner concrete pavements could be designed in the future at lower cost and reduced environmental impact.
... However, none of these studies provided any solution to improve the interpolation method. Godfrey [32] reported that increasing the number of weather stations provides good interpolation result. However, this solution is not always practical. ...
This study performed a sensitivity analysis to see the effects of different climates of New Mexico on pavement performance using the mechanistic empirical (ME) design analysis. Results show that the predicted distresses vary significantly for different climate conditions. However, there were only 13 weather stations available in New Mexico for the ME design climate database. These limited number of stations might not cover the complete territorial diversities of this large state. Furthermore, the existing data were outdated, and limited in length by year. To this end, this study updated the existing 13 weather stations to 2015 using the National Climate Data Center (NCDC) database. In addition, 11 new stations within the state, and 13 weather stations from surrounding states were included in climate database. Later, a comparative study was performed to see the effects of the climate change on predicted distresses in New Mexico. Results show that the climate change for a 10 years period have insignificant effects on pavement distresses. Then, the effectiveness of interpolation method for generating virtual station was investigated. Results show that the interpolation method is not effective enough to reflect the actual climate conditions for many sites. To solve this problem, a temperature zone map was developed using the NCDC database. The objective of this map is to select appropriate weather stations during interpolation. It is found that the temperature zone map reduces the error significantly. Therefore, this study suggests developing a temperature zone map when the number of the weather station is limited.
The coefficient of thermal expansion (CTE) of portland cement concrete (PCC) is a significant factor affecting the performance of concrete pavements. It is also required as a direct input in the mechanistic-empirical pavement design guide (MEPDG). The primary objective of this study was to determine CTE values of PCC mixes used in Hawaiian pavements. A secondary objective was to study the effect of curing time on the CTE. To achieve these objectives, 45 concrete specimens were prepared on-site at three Hawaiian concrete companies using local basaltic aggregates. For each site, 15 replicate test specimens (five sets of three) were cured in a 100% humidity room for 3, 7, 14, 28, and 56 days before determining their CTEs following AASHTO T 336. It was found that CTE values vary significantly with curing time. It was also observed that the CTEs at 28 days computed in this study, ranging from 6.1×10-6/°F to 6.6×10-6/°F (11.0×10-6/°C to 11.9×10-6/°C), differ significantly from the value recommended in the MEPDG manual of practice for concrete specimens with basaltic rock as a constituent (5.2×10-6/°F, 9.4×10-6/°C), which can lead to designs with overestimated performance. The variation caused by curing time is similar in magnitude to the variation caused by the use of different mixes for a given curing time. Thus, the study results support the need to establish a standard curing time when determining an appropriate CTE for design. Furthermore, use of a nonrepresentative default value can have a higher effect than that produced by differences between mixes or curing times, which highlights the importance of performing research to establish local CTE values. Based on the results, it is recommended to use the CTE obtained after 28 days of curing for design. Possible implications of the results obtained in this study are illustrated with a particular jointed plain concrete pavement (JPCP) design with the MEPDG.
Although many papers were published during the past decade on the coefficient of thermal expansion (CTE) and its impact on concrete pavement design, an error was recently discovered in the AASHTO TP60-00 about the calibration of the testing equipment and, consequently, determination of the concrete CTE. The new AASHTO T336-09, even though based on the TP60-00, rectifies this calibration issue. This paper presents differences between the two test methods and implications for the Long-Term Pavement Performance database and for the Mechanistic-Empirical Pavement Design Guide and for its implementation by state departments of transportation. Recommendations are provided for improvements to the AASHTO T336-09 test method.
Pavements are omnipresent in our society. From roads and airports to parking lots and driveways, every civil engineering project requires applications of this complex subject. Pavement Engineering covers the entire range of pavement construction, from soil preparation to structural design and life-cycle costing and analysis. It links the concepts of mix and structural design, while also placing emphasis on pavement evaluation and rehabilitation techniques. State-of-the-art content introduces the latest concepts and techniques, including ground-penetrating radar and seismic testing. The text facilitates a general course for upper-level undergraduates, covering the selection of materials, mix and structural design, and construction. It also provides laboratory and field tests accompanied by a discussion of new and advanced concepts. This unique text prepares the next-generation of engineers with the core principles and application knowledge needed to maneuver in the ever-expanding pavement engineering industry.
The coefficient of thermal expansion (CTE) is a fundamental property of concrete. It has long been known to have an effect on joint opening and closing in jointed plain concrete pavement, crack formation and opening and closing in continuously reinforced concrete pavement, and curling stresses and thermal deformations in both types of pavements. However, it has not been included as a variable either in materials specifications or in the structural design of concrete pavements. Hundreds of cores were taken from Long-Term Pavement Performance sections throughout the United States and were tested by FHWA's Turner–Fairbank Highway Research Center laboratory, using the AASHTO TP 60 test procedure. The CTE values were then assimilated into groups on the basis of aggregate types, and the mean and range of CTE were calculated. These results were then used in the new mechanistic–empirical pavement design guide to determine the significance of the measured range of CTE on concrete pavement performance. The CTE of the concrete was found to vary widely, depending on the predominant aggregate type used in the concrete. Sensitivity analysis showed CTE to have a significant effect on slab cracking and, to a lesser degree, on joint faulting. Its overall effect on smoothness was also significant. Given that CTE has not been used before in routine pavement structural design, the conclusion is that this design input is too sensitive to be ignored and must be fully considered in specifications and in the design process to reduce the risk of excessive cracking, faulting, and loss of smoothness.
Many highway agencies use AASHTO methods for the design of pavement structures. Current AASHTO methods are based on empirical relationships between traffic loading, materials, and pavement performance developed from the AASHO Road Test (1958–1961). The applicability of these methods to modern-day conditions has been questioned; in addition, the lack of realistic inputs regarding environmental and other factors in pavement design has caused concern. Research sponsored by the NCHRP has resulted in the development of a mechanistic–empirical design guide (M-E design guide) for pavement structural analysis. The new M-E design guide requires more than 100 inputs to model traffic, environmental, material, and pavement performance to provide estimates of pavement distress over the design life of the pavement. Many designers may lack specific knowledge of the data required. A study was performed to assess the relative sensitivity of the models used in the M-E design guide to inputs relating to portland cement concrete materials in the analysis of jointed plain concrete pavements. Twenty-nine inputs were evaluated by analysis of a standard pavement section and change of the value of each input individually. The three pavement distress models (cracking, faulting, and roughness) were not sensitive to 17 of the 29 inputs. All three models were sensitive to six of the 29 inputs. Combinations of only one or two of the distress models were sensitive to six of the 29 inputs. These data may aid designers in focusing on inputs that have the most effect on desired pavement performance.
The influence of high volume cement replacement using a combination of slag and limestone, on the hydration, reaction products and pore structure, and strength of cementitious systems is reported in this paper. Total replacement levels vary from 20% to 50% by volume. Slag is blended with: (i) Portland-limestone cement (PLC) that contains limestone interground with cement, or (ii) OPC and limestone of four different sizes in such a way that the resulting particle size distribution of the composite matches that of the corresponding PLC-based mixture. The hydration response of cement and cement-slag mixtures are found to be modified in the presence of limestone. It is observed from calorimetric and thermogravimetric analysis that a favorable slag-limestone synergy exists, that enables high volume replacement of cement without concomitant loss in properties. The early-age compressive strengths are beneficially impacted by the presence of limestone whereas the clinker factor does not play a significant role in later-age strengths in both the blended and interground systems. The study paves the way for development of multiple-material binders containing higher levels of cement replacement that demonstrate early and later age properties that are comparable to or better than that of traditional straight cement systems.